Speaker
Description
In cesiated radio-frequency (RF)-driven negative ion sources, beam divergence and spatial uniformity are strongly influenced by plasma transport processes and cesium dynamics in the source region. Since beam quality is closely linked to plasma behavior near the plasma grid, understanding the coupling between source plasma properties and extracted beam characteristics is essential for optimizing high-current negative ion beam systems. However, the quantitative relationship between source-region optical emission spectroscopy (OES) observables and beam properties remains insufficiently understood.
This work presents an integrated multi-diagnostic framework to investigate the correlation between plasma parameters and beam characteristics on the CRAFT RF-driven negative hydrogen ion source test facility. Balmer-series emissions (Hα, Hβ, and Hγ) measured near the plasma grid are analyzed to derive spectroscopic indicators associated with local plasma behavior. Effective plasma parameters are inferred using an ADAS-based collisional-radiative model, enabling the characterization of plasma conditions relevant to negative ion production and transport.
Beam properties, including divergence and spatial uniformity, are characterized through the combined use of beam emission spectroscopy, visible-light imaging, water-flow calorimetry, and secondary electron diagnostics. Plasma and beam observables acquired under varied operating conditions, including variations in source and extraction parameters, are synchronized to establish a source-beam parameter database for systematic correlation analysis.
The study seeks to improve the understanding of source-beam coupling mechanisms in cesiated RF-driven negative hydrogen ion sources and to support the development of spectroscopy-assisted diagnostic and optimization strategies for negative hydrogen beam systems relevant to neutral beam injector applications.
| Email address | na.wang@ipp.ac.cn |
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| Visitor's Visa | yes |
| Classification | H- and D- sources for fusion, accelerators and other applications |